This invention relates generally to apparatus and method for transmitting coded signals from one place to another. More particularly, this invention relates to an optical encoding system. Still more particularly this invention relates to the use of a holographic element and a fiber optic array to transmit encoded signals.
It is desirable in many signal transmission applications to have the capability of sending an encoded signal without requiring an electrical power input at the encoder. The ability to provide rotary and linear position encoding without an electrical power input provides freedom from electromagnetic interference and other environmental effects. Some previous optical encoders require arrays of directional couplers to read out the various tracks. Other previous encoders are analog devices that have high sensitivity to environmental parameters such as optical source power, temperature changes and fiber loss.